Covadonga shark tooth: a 331-million-year-old giant found in Asturias

The tooth is 43 millimetres tall, the greatest height recorded for its genus, Carcharopsis (the exact species is still undecided). The cusp is wide and curved, with doubly serrated edges. The tiny enamel serrations match those of today's tiger shark, built to cut through flesh and even shells. The authors describe a hypercarnivorous diet.

How big was the shark?

Using proportion models based on the great white and the tiger shark, the team estimates 5 to 6 metres. A large tiger shark measures 3.8 to 4.5 metres, and almost none exceed 5. There is a catch: the figure comes from analogy with living sharks, not from a skeleton. Cartilage rarely fossilises, which is why most shark fossils are teeth.

Why it matters

Most Carcharopsis fossils come from southern Laurussia, now North America and part of Europe. This is the first from northern Gondwana, which the team takes as evidence that the shark moved between coastal waters and open sea. The area was then the shore of a warm tropical sea. The tooth sat at the base of a carbonate pile, in reddish nodular griotte limestone. A 2003 study argues the same stone was used to build the basilica, and quarries in Amieva and Llanes sold it as “Rojo Covadonga” in 2000.

The date falls in the Mississippian, after the Hangenberg event ended the Devonian. Jawed vertebrates lost 32% of their genera, according to a 2010 study, and armoured placoderms such as Dunkleosteus vanished. Sharks, ray-finned fishes and tetrapods then diversified. A 5 to 6 metre predator at the top suggests, per the authors, that the food chain had already been rebuilt.

Carcharopsis reigned for millions of years. Its decline coincided with the mid-Carboniferous crisis, which brought new shark lineages with scissor-shaped teeth. That crisis came with ice, and the Covadonga tooth predates it.